JPH0550827A - Air suspension for automobile - Google Patents

Abstract

PURPOSE:To obtain an excellent feeling to ride and driving stability by automatically adjusting damping force of a shock absorber. CONSTITUTION:Supply/discharge of compressed air to/from air springs 1R, 1L are controlled so as to provide fixed car height detected by a height sensor 17. A pressure of air in the air springs 1R, 1L is detected by an air switch 16, and in a control unit 10, shock absorbers 2R, 2L are switched to a soft side, when the low pressure of air is detected, and switched to a hard side when the high pressure of air is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air suspension for an automobile, which is intended to improve riding comfort.

[0002]

2. Description of the Related Art A suspension is provided between an axle and a vehicle body, and has the role of connecting the two to each other and absorbing the impact from the road surface to improve the riding comfort. The two main components of the suspension are the spring and the shock absorber that appropriately suppresses the vibration.

An air suspension that employs an air spring is called an air suspension. Normally, the supply / discharge of compressed air to / from the air spring is automatically controlled so that the vehicle height is kept constant irrespective of the number of passengers and loading conditions such as luggage. On the other hand, some shock absorbers
There are things that can change the damping force.By changing the manual switch, for example, in the city area, the damping force is weakened to make it softer and the riding comfort is improved, and on mountain roads with many dirt and curves, the damping force is strengthened to make it hard and driving stability is improved. Is improving.

[0004]

In buses and trucks, the sprung mass changes significantly depending on the number of passengers and the amount of luggage. In order to obtain a good riding comfort, it is necessary to weaken the damping force of the shock absorber when the sprung weight is light, and to strengthen the shock absorber damping force when the sprung weight is heavy. However, in the past, switching between software and hardware of the shock absorber was done manually, which was troublesome.

In view of the above-mentioned prior art, it is an object of the present invention to provide an air suspension for a vehicle capable of automatically adjusting the damping force of a shock absorber according to the sprung weight.

[0006]

The structure of the present invention for solving the above-mentioned problems has an air spring, a shock absorber whose damping force can be varied, and a height sensor for detecting the vehicle height, which is detected by the height sensor. In an automobile air suspension that controls the supply of compressed air to the air spring so that the vehicle height is almost constant, a pressure sensor that detects the pressure of compressed air in the air spring and the detected pressure detected by this pressure sensor However, when the pressure exceeds the set value, the damping force of the shock absorber is strengthened, and when the detected pressure is smaller than the set value, the control unit is controlled to weaken the damping force of the shock absorber.

[0007]

When the weight on the spring is heavy, the air pressure of the air spring is increased to keep the vehicle height constant. When the air pressure of the air spring rises like this, the shock absorber is automatically switched to the hard side. When the sprung weight is light, the air pressure of the air spring is lowered to keep the vehicle height constant. When the air pressure of the air spring becomes low, the shock absorber is automatically switched to the soft side.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows a configuration of a rear air suspension of a small bus to which the present invention is applied, and FIG. 2 shows an air system and a signal system of this rear air suspension. In FIG. 2, the air pipe is shown by a solid line and the signal line is shown by a dotted line.

First, the structure and operation of the air suspension will be described with reference to FIGS. Left and right air springs 1
The R, 1L and the shock absorbers 2R, 2L are provided between the highly rigid frame 3 and the axle supported by the leaf spring 4. Shock absorber 2R, 2L
The damping force can be switched to three levels: soft (small damping force), middle (medium damping force), and hard (large damping force).

The compressed air discharged from the electric air compressor 5 is sent to the reserve tank 8 through the air dryer 6 and the check valve 7 and stored therein. Air switch 9
Detects the air pressure in the reserve tank 8, and a detection signal is sent to the control unit 10. Then, the control unit 10 controls so that the air compressor 5 operates when the air pressure in the reserve tank 8 is below a certain value, and stops when the air pressure in the reserve tank 8 exceeds a certain value. .. When the air pressure in the reserve tank 8 becomes excessive, the safety valve 11 is opened to reduce the air pressure in the tank. In addition, the air dryer 6 is used when the compressed air is discharged from the air dryer 6 to the atmosphere to discharge water and to be dried.
A way type magnet valve 12 is provided.

When the magnet valves 13 and 14 are in communication with each other, the compressed air in the reserve tank 8 is sent to the surge tanks 15R and 15L and the air springs 1R and 1L. The air pressure in the air springs 1R and 1L is detected by the air switch 16, and this detection signal is sent to the control unit 10.

The vehicle height is detected by the height sensor 17,
This detection signal is sent to the control unit 10.
Further, a manual switch 18 is connected to the control unit 10.

Next, referring to FIG. 3, the control operation centered on the control unit 10 will be described. The vehicle height is detected based on the detection signal of the height sensor 17. When the vehicle height is low, the magnet valves 13 and 14 are placed in a communicating state to supply air to the air springs 1R and 1L to extend the air springs 1R and 1L (steps 1 and 2). When the vehicle height is high, the magnet valve 13 is opened to the atmosphere and the magnet valve 12 is opened, and the air springs 1R and 1L are deflated to contract the air springs 1R and 1L (steps 3 and 4). When the vehicle height is the set height, the magnet valve 14 is closed to stop the air supply / discharge to / from the air springs 1R and 1L, and the vehicle height at that time is maintained.

The air switch 9 is turned on when the air pressure in the reserve tank 8 is below a set value, and is turned off when the air pressure inside the reserve tank exceeds the set value. Therefore, when the air switch 9 is turned on, the air compressor 5
Is activated (steps 5 and 6), and the air switch 9 turns off.
When it becomes F, the compressor 5 is stopped (steps 5 and 7).

The air switch 16 is an air spring 1.
It turns on when the air pressure in R, 1L exceeds a set value, and turns off when it falls below the set value. The controller 10 varies the damping force of the shock absorbers 2R, 2L according to the air pressure state of the air springs 1R, 1L.

That is, when the air pressure of the air springs 1R and 1L is high, the shock absorbers 2R and 2L are made to be hard or middle, and when the air pressure of the air springs 1R and 1L is low, the shock absorbers 2R and 2L are made to be soft or middle. (I) That is, when the air pressure of the air springs 1R and 1L is high and the air switch 16 is turned on, if the manual switch 18 is on, it is hard (a large damping force), and if the manual switch 18 is off, it is a middle (damping). (Steps 8, 9, 10, 11). (Ii) Further, when the air pressure of the air springs 1R and 1L is low and the air switch 16 is turned off, if the manual switch 18 is on, it is middle (during damping force), and if the manual switch 18 is off, it is soft (damped). (Small power) (steps 8, 12, 11, 13).

As described above, in this embodiment, the shock absorbers 2R, 2L are automatically switched to the hard side when the air springs 1R, 1L have high air pressure due to a large amount of occupants and luggage and a large sprung weight. The shock absorbers 2R, 2L are automatically switched to the soft side when the occupant and the load are small and the spring weight is light and the air pressure of the air springs 1R, 1L is low. Therefore, excellent riding comfort and steering stability can be obtained.

[0018]

As described in detail with reference to the above embodiments, according to the present invention, the damping force of the shock absorber is automatically controlled according to the air pressure of the air spring. It is possible to obtain excellent riding comfort and steering stability even without the presence of.

[Brief description of drawings]

FIG. 1 is a perspective view showing an air suspension of the present invention.

FIG. 2 is an explanatory diagram showing a control system of the air suspension of the present invention.

FIG. 3 is a flowchart showing a control system of the present invention.

[Explanation of symbols]

 1R, 1L Air spring 2R, 2L Shock absorber 3 Frame 4 Leaf spring 5 Air compressor 6 Air dryer 7 Check valve 8 Reserve tank 9 Air switch 10 Control unit 11 Safety valve 12, 13, 14 Magnet valve 15R, 15L Surge tank 16 Air switch 17 Height sensor

Claims (1)

[Claims] 1. An air spring, a shock absorber capable of varying a damping force, and a height sensor for detecting a vehicle height. Compressed air to the air spring so that the vehicle height detected by the height sensor is substantially constant. In the air suspension of the automobile that controls the supply of the pressure sensor, the pressure sensor that detects the pressure of the compressed air in the air spring, and when the pressure detected by this pressure sensor exceeds the set value, the damping force of the shock absorber is increased, An air suspension for an automobile, comprising: a control unit that controls so as to weaken the damping force of the shock absorber when the detected pressure is smaller than a set value.